海河水利

针对黄土高原重大工程场地挖方坡面降雨侵蚀严重、治理难度大、植被恢复困难、侵蚀治理容易反复等问题，基于2021年延安市羊圈沟流域挖方坡面径流小区14场野外降雨下泥沙监测数据，利用WEPP模型模拟不同工况下挖方坡面侵蚀情况。结果表明，坡面侵蚀量随着坡度的增加先增加后减少，侵蚀量存在极值，对应坡度为临界坡度56°，坡面侵蚀量与坡度关系在0～20°时呈现指数关系，大于30°时呈现开口向下的抛物线关系；坡长与挖方坡面侵蚀量在坡长不大（<40 m）时呈现指数关系，坡面侵蚀量与坡长关系曲线存在上界；降雨强度大更容易造成坡面侵蚀，且侵蚀量与降雨强度线性相关，侵蚀量增加速率与坡度无关，与坡长负相关但不为负；结合挖方工程实际需要，坡度70°左右最佳，坡长建议在2 m左右。研究对重大工程场地挖方作业、挖方坡面侵蚀防治与生态恢复具有实际指导意义。

Addressing severe rainfall erosion on excavated slopes in major engineering sites on the Loess Plateau—characterized by management difficulties, challenging vegetation restoration, and recurring erosion—this study utilized 2021 field monitoring data from 14 rainfall events at runoff plots on excavated slopes in the Yangjuangou watershed of Yan'an City. The Water Erosion Prediction Project(WEPP) model was used to simulate slope erosion under different conditions. Results indicated that: Slope erosion initially increased with slope gradient and then decreased, with an extremum corresponding to a critical slope gradient of 56°. The relationship between slope erosion and gradient was exponential at 0°–20° and parabolic(opening downward) above 30°. For short slope lengths(<40 m), the relationship between slope length and erosion was exponential, with an upper limit to the curve of erosion versus slope length. Higher rainfall intensity caused more significant slope erosion, and the erosion volume was linearly correlated with rainfall intensity. The rate of erosion increase was independent of slope gradient but negatively correlated with slope length, though not to a negative extent. Considering practical excavation needs, a slope gradient of approximately 70° and a slope length of around 2 m were recommended. This study provides practical guidance for earthwork operations, erosion control, and ecological restoration of excavated slopes in major engineering sites.